Projection display systems tend to operate in a high temperature environment due to the internal lamp assembly used to provide illumination flux to the system. A particularly critical component is the spatial light modulator (SLM), such as a DMD or other micro-electro mechanical system device, where the illumination is focused on to its surface to be modulated and then reflected onto a display screen. It is essential that these devices be properly cooled to a specified operating temperature range for reliable, long life operation of the projector.
Traditionally, projection display devices have been cooled by attaching an air-cooled heat sink to the SLM. Heat dissipated in the SLM is then transferred to the air surrounding the heat sink, which is enclosed inside the projector chassis and often preheated by other components relative to the ambient air temperature outside the projector. A typical conventional cooling approach is shown in FIG. 1. An SLM package 100 with optically transparent cover glass 102 is mounted on a printed wiring board (PWB) 104. A metal heat sink stud 106 is attached to the bottom side of the SLM package and extended through a hole in the PWB 104. A heat sink 108, with fins to provide a large surface area, is attached to the stud 106 by a means that provides a good thermal interface. A fan 110 is mounted to blow air 116 across the heat sink, removing heat through convection, and out through vents 114 in the projector chassis 112. Even though outside air is brought into the enclosed chassis, it is preheated by the time it reaches the heat sink, and as a result the cooling effectiveness is limited.
Other methods conduct heat directly from the display device to the system's chassis wall so that heat is transferred from the chassis wall to the lower temperature ambient air surrounding the outside of the system. However, due to manufacturing tolerances in the parts, these approaches do not always provide optimal contact at the interfaces along the thermal path.
As projection systems become smaller, reducing the available space for cooling systems, and the light sources become brighter, improved display device cooling is required.
What is needed is an adjustable mechanism that allows the space between the SLM and the chassis wall to be tightly closed, thereby assuring a good thermal path. The solution of the present invention meets this need by providing a direct thermal path between the SLM package and the chassis wall, which consists of an adjustable mechanical linkage. Multiple embodiments of adjustable mechanical linkages are disclosed herein.